Group H

Machinability of workpiece materials

Typical group H materials are heat-treated materials such as hardened and martensitic steels.

As the classification name explains, these materials can be extremely hard and easily

cause tool wear.

Also depending on the type of heat treatment, only the surface could be very hard. This means care should be taken to select a tool that is resistant to notch wear.


Although cutting resistance becomes relatively high, the effects of the hardness are extreme which means that the emphasis is not placed so much on combating cutting resistance but on tool life against the hardness of the material.

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Mould core, example of group H component.